Central bankers are in a bind. It’s their job to shift policy levers, nudging interest rates higher and lower, to boost jobs and keep prices, or inflation, at the optimal level. That means not too high, and not too low.

Inflation affects prices — milk, train tickets, everything.

It has been stubbornly low for years. And low inflation can hurt the economy: Businesses get queasy about investing in people and equipment. If prices don’t rise, wages don’t either.

The problem is that interest rates, which the Fed influences through its federal funds rate, remain low even though jobs recovered years ago. The funds rate effects what people pay on things like mortgages and credit cards. Lower rates promote growth.

In other words, inflation is signaling that the Fed should not increase rates. But economic growth and low unemployment of 4.4% are saying it should.

The other policy decision on Yellen’s agenda involves the Fed’s so-called balance sheet. That’s the enormous amount of debt — mostly Treasury bonds and securities backed by mortgages — it racked up during the financial crisis.

The central bank effectively lent trillions of dollars to the government to spur the economy and make it cheaper for everyone to borrow. And now it’s time for the Fed to begin selling that debt.

Several Fed officials have signaled the central bank could take a first step in selling off its bonds and other investments starting next month.

An announcement that the Fed will start unwinding its debt would mark yet another milestone in an economic recovery now in its ninth year.